<?xml version="1.0"?>

<!DOCTYPE zoo [
    <!ATTLIST species id ID #REQUIRED>
]>

<zoo>
  <class>
    <name>Reptiles</name>
    <species id="Chamaeleo-chamaelon" name="Chameleon" specimens="2"/>
  </class>
  <class>
    <name>Birds</name>
    <species id="Dromaius-novaehollandiae" name="Emu" specimens="12"/>
    <species id="Tyto-alba" name="Barn Owl" specimens="4"/>
    <species id="Corvus-corax" name="Raven" specimens="0"/>
    <location>Aviary</location>
  </class>
</zoo>
